Rationale and long-term objectives: Adult studies have shown that adiposity, especially visceral adipose tissue (VAI), and cardiovascular (CV) fitness are key links between lifestyle factors like diet and exercise on one hand, and CV disease on the other. However, very little is known about these links during the juvenile years, when the processes leading to CV disease are at an early stage of development. The specific aims are as follow: (1) to determine the relations of free-living diet and exercise to total body percent fat ( percentBF), VAT and CV fitness in black and white boys and girls of varying SES. (2) to determine the relations of fatness and fitness to different CVD risk factors. Design and methods: (1) Recruit 800 15 to 18 year olds, 200 in each ethnicity and gender subgroup. (2) Assess diet with seven 24-hour recalls, and exercise with two seven-day recalls and heart rate monitoring. (3) Measure percent body fat with dual-energy x-ray absorptiometry, VAT with magnetic resonance imaging and CV fitness with a multi-stage treadmill test. (4) Measure major fatness- and fitness-related CV disease risk factors (e.g., total cholesterol:HDL cholesterol ratio, insulin, systolic blood pressure, left ventricular mass indexed to height, fibrinogen). (5) Conduct multivariate and univariate analyses to determine relationships. Health relatedness: The investigators state that the provided by this project will assist in the formulation of effective lifestyle interventions targeted to specific demographic groups for primary prevention of CVD, starting early in life when the foundations for adult disease are being laid.